The invention relates to a method for vulcanizing tires, in which the tire being vulcanized is placed in a mold in the area of a tire heating press and the mold is heated, and in which a heat transfer fluid is conducted into the area of the inner surface of the tire.
The invention further relates to a device for vulcanizing tires, comprising at least one heatable mold for the tire being vulcanized as well as a conduit device for a fluid intended for heat transfer, wherein the conduit device can be connected to a bellows.
Heating presses known thus far have a flexible inflatable cushion element as the bellows. The inflating is typically done with compressed air and/or hot steam. An internal pressure of the bellows during the vulcanization often lies in a range of 10 bar to 30 bar.
The bellows has a diameter similar to the outer diameter of the tire. The forces generated by the internal pressure are transmitted by the entire surface of the bellows onto the molds of the heating press and often require a closing pressure of several hundred metric tons. This results in the known very stable designs of heating presses and the consequent production costs.
Actually, only a small encircling ring portion of the circumference of the bellows situated on the outside in the radial direction is used to support the tire blank. For tires with a tread profile, this profile is produced by pressing into the mold. After the completion of the vulcanization process, an intermeshing of the tire tread with the mating profile of the mold therefore exists. This means that two-piece molds can only be used for tires with slight tread profiling. For larger tread profilings, the molds of the tire heating press are provided with segments able to move radially apart from each other, in order to eliminate the form fit created by the vulcanization.
One problem which the invention proposes to solve is to design a device such that the required closing forces of a tire heating press can be substantially reduced.